The present invention relates to a system for the transmission of high definition pictures via a relatively narrow passband channel, the system comprising a transmission part formed by a picture pick-up member for providing said pictures which are constituted by a plurality of picture elements or samples distributed over even and odd lines, a filter member for filtering said samples, a sub-sampling circuit for taking certain samples of said filtered samples from the output of the filter member and a transmission circuit for transmitting said certain samples via the channel in accordance with transmission fields, and also at least one receiving part formed by a receiving circuit for receiving the certain samples coming from the transmission circuit, an interpolation member for recovering samples on the basis of the received certain samples and a first display circuit for reconverting the recovered samples and the received certain samples into a restored high-definition picture.
The present invention also relates to a transmitter and a receiver suitable for the system.
Systems of this type are well known and are used with great advantage more specifically in the transmission of high definition pictures which are compatible with the "MAC" standards and more particularyly the "D2-MAC" standard (recommendation 601 of the C.C.I.R.).
A prior art system of this type is described in the article "A SINGLE CHANNEL HDTV BROADCAST SYSTEM-THE MUSE-" by Yuichi Ninomiyha et al..., published in the periodical "NHK LABORATORIES NOTE" vol. 304 of Sept. 1984. This MUSE system, which is not adapted to the said standards, can easily be rendered suitable for these standards by linearly modifying its characteristic parameters. This known system utilizes, for the transmission of the samples of a picture, a sampling structure which extends over four fields. Picture elements belonging to the differential spatial positions are transmitted in these four consecutive fields; when the processed picture is a still picture, a good quality is obtained. On the other hand, the transmission in four fields does not render it possible to obtain a good quality for the recovery of moving pictures whose portions move perceptibly during four consecutive fields.